show: implement underway view This is the beginning of a wip/smartlog view. It is basically a manually constructed (read: fast) revset function to collect "relevant" changesets combined with a custom template and a graph displayer. It obviously needs a lot of work. I'd like to get *something* usable in 4.2 so `hg show` has some value to end-users. Let the bikeshedding begin.

show: fix formatting of multiple commands Because we're formatting to RST, short lines wrap and there needs to be an extra line break between paragraphs to prevent that. In addition, the indentation in the old code was a bit off. Refactor the code to a function (so we don't leak variables outside the module) and modify it so it renders more correctly.

pycompat: import correct cookie module on Python 3 http.cookielib doesn't exist. http.cookiejar does and it contains the symbols we need. This fixes test failures on Python 3.